Japanese authorities want to study how radioactive cesium impacts marine life to determine how they can replenish local fish stocks harmed by the Fukushima nuclear disaster that exploded earlier this year.

Starting next month, the prefectural fisheries experiment station in Iwaki will begin an experiment study to see how fish and shellfish absorb cesium and how long it will be take to lower the effects of cesium. Researchers will keep marine life in cesium-laced water tanks during the study.

Coastal fishing off Fukushima has been suspended; the study aims to secure the safety of marine life for the future recovery of the prefecture’s fisheries.

A survey finished earlier this month by the prefectural fisheries experiment station found that levels of radioactive cesium surpassing the government's provisional safety limit of 500 becquerels per kg were identified in 18 out of 94 types of fish and shellfish caught off Fukushima, Mainichi Japan reports.

However, cesium in white bait was not detected in September even though 850 becquerels of cesium were found in the fish in May. Meanwhile, levels of cesium three times the provisional limit have been observed in some flatfish.

Why the effect of cesium differs depending on fish species and even individual fish remains a mystery.

The Oceanographic Society of Japan believes the government should release radiation readings in sea water even if it is below the minimum measurement level, because even then the radioactive elements may be dangerous when concentrated in seafood, Bloomberg reports.

“Depending on the species, fish have been known to accumulate as much as 100 times the amount of pollutants in the environment,” pointed out Jota Kanda, a professor at Tokyo University of Marine Science and Technology specializing in marine environment.

The fisheries experiment station will conduct the research with the Fisheries Research Agency, a Yokohama-based independent administrative institution.

They have already started keeping red sea bream and will begin gathering several other species including flatfish, abalone and sea urchin.

Scientists will hold uncontaminated fish and shellfish in radiation-contaminated water and keep contaminated fish in uncontaminated seawater. They hope to establish the relationship between the concentration of contamination in seawater and the level of resulting contamination and also how long it will take to reduce it.

"If we could reveal how radiation affects marine products, we can establish the means to secure seafood safety. We are committed to producing results that can help the recovery of local fisheries," said Satoshi Igarashi, head of the fisheries experiment station.

Although the ban on offshore fishing was lifted in Fukushima in June, coastal and trawl fishing remain suspended out of radiation contamination concerns.

Fukushima’s federation of fisheries cooperative associations decided last week that the ban will continue through October, but it did begin to consider resuming on an experimental basis the fishing of octopus, squid and other species whose levels of cesium are within the safety limit.

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